Composite lake pigment



Patented July7, 1931 UNITED STATES PATENT OFFICE WILLIAM HENRYWHATMOUGH, OF LONDON, ENGLAND, ASSIGNOR TO STANDARD PRODUCTSCORPORATION, A CORPORATION OF NEW YORK COMPOSITE LAKE PIGMENT" .NoDrawing. Original application filed January 30, 1926, Serial No. 85,025,and. in Great Britain December 7, 1925. Divided and this applicationfiled. August 25, 1926.

This invention relates to composite lake pigments containing oleaginoussubstances and includes the process of manufacturing these novelpigments.

' It is desirable to incorporate lake pigments in dispersions of oils,waxes and similar oleaginous materials for use in typewriter ribbons,carbon paper and many other uses. Hitherto, such incorporation has beenmade by dispersing the finished pigment in the dispersion of oleaginoussubstances in water or in other oleaginous media. This procedure hasbeen open'to many disadvantages as in the case of numerous pigments, itis difiicult to satisfactorily disperse them and as the dis perslons arefrequently not stable over long periods of time, it has been necessaryto use the dispersion very shortly after formation or to incorporaterelatively large amounts of 6 stabilizers or deflocculating agents, suchas gums and the like which are frequently undesirable.

It is an object of the present invention to prepare composite lakepigments containing oleaginous materials which can be readily and easilydispersed in dispersions of the oleaginous material in water or in otheroleaginous media and which will keep in a paste or powder form withoutthe aid of stabilizing agents. Other and further objects will appearfrom the more detailed description of the invention which follows.

According to the present invention, lake pigments, either simple orcomplex. are precipitated in a dispersion of the oleaginous materialdesired. The precipitated pigment carries down substantially all of theoleginous material within wide limits and the resulting product which isusually in the form of a powder or paste can be washed with water toremove soluble salts with little or no loss of the oleaginous component.The product keeps well and can be readily dispersed in a suitabledispersing medium with a minimum of effort.

The lake pigments of the present invention may be simple or complexpigments, that is to say, they may be formed by a reaction between thedye and the substrate or an insoluble pigment may be precipitated orstruck on Serial No. 131,550.

the substrate by causing the dye to react with other compounds in thepresence of the substrate. The formation of the lake in each case takesplace in the presence of a dispersion of the desired oleaginousmaterial, which is practically completely precipitated with the pigmentwithin wide limits.

The formation of the lake pigment may be carried out in various ways,all of which are included in the invention. Thus, a dispersion of theoleaginous material in water can be incorporated with a solid substrate,the latter being homogeneously dispersed throughout the mixture. ponentsof the colored pigment may then be added to the dispersion of oleaginousmaterial and substrate. Pigments may also be made by dispersing theoleaginous material in a dispersion of the substrate or in a solution ofone or more'of the soluble pigment components. If the oleaginousdispersion is in the presence of the substrate, the pigment componentsmay be added in the form of water solutions or oleaginous dispersions.If the primary volume of oleaginous dispersion is in the presence of oneof the pigment components, the substrate should then be dispersedthroughout the mixture before adding the final pigment component whichbrings about precipitation of the final product. There are many otherpossible combinations which are included within the invention, and itshould be understood that the invention in its broader aspects is notconcerned with the particular order in which the various components ofthe dispersions are introduced.

Solutions containing the com- A very large number of lake pigments can ibe prepared and are included in the present invention, which is not inany sense limited to the pigments which will be described by way ofspecific example, and which are intended to be illustrative of theinvention without in any sense limiting it. The oleaginous materialwhich can be used to form the dispersion includes a large number ofmaterials which are characterized by their physical oiliness. Forexample, dispersions of carnauba wax, beeswax, mineral oil, petrolatum,castor oil, linseed oil and. simila products may be used,

lVhile these compounds differ widely in their chemical characteristics,they all possess the physical characteristics of oiliness or waxiness,on which their utility in the present invention depends. Accordingly,the word oleaginous is intended to relate to the physical characteristsof the product and not to their chemical nature. Single oleaginousmaterials may be used, or a mixture of different materials.

The character of the substrate which is used in the formation of thelake pigments of the present invention is not limited by the specificpigments which will be described. On the contrary, any base material orsubstrate, such as barium sulphate, aluminum hydroxide and other wellknown materials may be used as substrates on which to strike a dye,which may be a coal tar dye or any other suitable dye.

Example I 60 kg. of methyl violet are dissolved in 500 l. of a 25%aqueous carnauba wax dispersion. 30 kg. of a finely divided prel aredwhite base consisting of barium sulphate and alumina is added withvigorous agitation followed in order by 45 l. of a 2% tartar emeticsolution, 40 l. of a 2% tin chloride solution, 60 kg. of tannin and 100l. of a 10% sodium carbonate solution. The purple lake precipitates outand carries down with it the wax, producing a soft purple solid whichcan be purified by decanting the liquid and washing with water 7 toremove soluble salts.

Example I] 60 kg. of Victoria blue are dissolved in 500 l. of a 25%aqueous mineral oil emulsion. 30 kg. of a finely divided prepared whitebase, consisting of barium sulphate and alumina is added with vigorousagitation ,thereupon 45 l. of a 2% tartar emetic solution, 35 l. of a 2%tin chloride solution, 60 kg. of tannin and 1.00 l. of a 10% sodiumcarbonate solution are added in order. 7

The blue lake precipitates carrying with it all of the mineral oil andforms a soft liquid paste, which can be washed with water to removesoluble salts. The product can be used for a pigment in typewriterribbons by i11- corporating in a suitable oleaginous emulsion. Ifdesired, lard oil emulsions may be used instead of mineral oilemulsions.

I Example [I] 30 kg. of a white ba e, consisting of barium sulphate andalumina is prepared by the reaction of solutions of suitable quantitiesof alum sodium carbonate and barium chloride in about 500 l. of a 25%aqueous carnauba sodium carbonate solution are added in order. Thepurple lake precipitates out, carrying down with it all of the carnaubawax and producing a product substantially the same as that in Example 1.

It is an advantage of the present invention that the amount and natureof the oleaginous material incorporated with the lake pigments can beaccurately controlled, since in the case of most oleaginous dispersions,the pigment will carry down substantially all of the oleaginous materialwithin wide limits and will retain the material even when washed toremove soluble constituents. It is thus possible to incorporate thedesired amount of oleaginous material with the lake pigment in a singleoperation, which makes it possible in many cases to manufacture a finalproduct, such as a pencil lead composition requiring a large proportionof hard oleaginous material, in a single manufacturing operation.

7 In general, the use of stabilizers, such as gums, to maintain theoleaginous dispersion is undesirable, although small amounts may beunobjec'tionable in certain cases. Where a stabilizing agent is desired,a small amount of alkali or a soap may be incorporated with theoleaginous dispersion and such stabilizing agents are included withinthe scope of the present invention.

I am not sure just what the reaction is which brings about theincorporation of oleaginous material with the pigments, but while theinvention is not limited to any theory, I am of the opinion that thephenomen is essentially physical and that no definite chemical compoundis formed between'the pigment and the oleaginous mate rial. I am of theopinion that the colloidal particles of precipitating pigment areelectrically charged and of opposite sign to the particles of theoleaginous material and that the latterare therefore attracted to thepigment particles, adhering thereto or being adsorbed thereon. I havenot been able to definitely prove this theory and while I am of theopinion that it is the most probable explanation, it is possible thatlater research will bring to light other causes.

The products of the present invention are, of course, very different innature depending on the ingredients and the amounts of oleaginousmaterial incorporated in the product. They are all, however,characterized by easy dispersion in suitable media and are physicallyvery homogeneous showing a homogeneous texture under the microscope.

In the claims, the expression oleaginous material is intended to coveroily,-fatty and waxy bodies, irrespective of their chemicalclassification and includes not only fats and oils of the glyceridetype, but also hydrocarbon oils and waxes such asmineral oil, paraffinand the like. .Wax alcohols and other;

chemical compounds of similar physical charactoristics are alsoincluded, the term oleaginous being intended to refer to the physicalcharacteristics of the material and in no way to the chemicalcharacteristics.

The term lake will be limited to pigments which are prepared by strikingdyes on insoluble substrates and does not include pigments prepared byprecipitating mineral pigments on to substrates.

I have used the phrase adsorbed with in a non-technical sense toindicate that the par ticles of the pigment are held to the particles ofthe dispersed oleaginous material by some attractive force or surfacecharacteristic. I do not wish to be bound by any strict meaning of theword adsorbed nor do I wish thereby to indicate definitely whether theparticles of pigment are held on the surface of the dispersed particlesof the oleaginous material or the oleaginous material covers or wets thesurface of the pigment particles so as to enclose them within a film ofthe oleaginous material. The fact is, so nearly as I now am able todiscover, that the pigment particles and the oleaginous particles dojoin together in some manner so that the precipitated particles ofpigment are isolated, thus inhibiting further coalescence between themwhich would make necessary grinding of the pigment to again reduce itsparticle size.

This application is a division of my prior application, Serial 85,025,filed January 30, 1926.

Having thus described my invention, what I desire to secure by LettersPatent of the United States and claim is:

1. The process of preparing a composite pigment which comprisesdispersing a finely divided substrate in an aqueous dispersion ofoleaginous material and striking a dye on said substrate to form a lakepigment whereby the pigment particles are precipitated and carry downwith them the oleaginous material.

2. The process of preparing a composite pigment which comprisespreparing a dispersion of a substrate and an oleaginous material in aliquid medium containing a dye and striking the dye onto the substrateand simultaneously causing the oleaginous material to be adsorbed withthe resulting pigment.

3. The process of preparing a composite pigment which comprisespreparing a dispersion containing a substrate and an oleaginous materialin colloidally dispersed form, adding a dye to said solution, strikingthe dye onto the substrate in the presence of the dispersed oleaginousmaterial and precipitating the resulting pigment so that it is adsorbedwith the oleaginous material.

4. The process asdefined in claim 3 in which the dispersion is made bychemical precipitation of the substrate from a solution in which theoleaginous material is dispersed and the dye is struck onto theresulting substrate by GERTIFIGATE 0F GQRRECTION.

Patent No. 1,813,371. Granted July 7, 1931, to

WILLIAM HENRY WHATMOUGH.

Signed and sealed this 25th day of August, A. D. 1931.

peciiication of the Page 2, line 46, for the letters Patent should beread with nform to the record of the case in M. J. Moore, (Seal) ActingCommissioner of Patents.

